Europe and Iran will put on a united front in support of the landmark 2015 nuclear deal at talks in Brussels Thursday. The UK, France, and Germany - the European powers that helped negotiate the accord to curb Iran's nuclear program in return for lifting sanctions - will reassure Tehran they remain committed to it. They're taking this stand as US President Donald Trump is due to decide whether to extend waivers on nuclear-related sanctions against Tehran. Trump refused to certify that Iran was complying with the deal in October last year, and has repeatedly criticised and threatened to leave the accord.